JP2515130B2 - Pneumatic radial tires - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pneumatic radial tire.

Conventional technology Generally, in a pneumatic radial tire, a large shearing force acts between the plies at the belt ends due to diameter expansion based on internal pressure filling and ground contact deformation based on load rolling, which causes belt end separation. Sometimes. In order to prevent such a situation, conventionally, a cap having a strong rattling effect is arranged outside the belt layer in the radial direction so as to cover the entire width of the belt layer. A cord that intersects with the equatorial plane of the tire within an angle range of 10 degrees or less is embedded inside.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a pneumatic radial tire, since the cap covers the belt layer over the entire width, the belt layer is not limited to the central portion in the width direction, but to both side edges in the width direction. The rigidity of the part is also high and it becomes difficult for it to deform. Here, since the crown portion of the pneumatic radial tire is generally convex, the radius of the center portion is larger than the radius of the shoulder portion. From such a fact, when the pneumatic radial tire is ground-deformed due to load rolling, the belt layer resists the deformation, and the difference in radius between the center portion and the shoulder portion becomes difficult to be absorbed,
The ground contact pressure at the shoulder portion is reduced. Therefore, the shoulder portion is easily dragged, slippage occurs between the shoulder portion and the road surface within the ground contact surface, the shoulder portion is worn away, and uneven wear such as shoulder drop occurs. is there.

In order to solve such a problem, for example, JP-A-54-
As described in Japanese Patent No. 126308, when the width of the reinforcing ply is narrowed to facilitate the deformation of both widthwise end portions of the belt layer, the radius difference between the shoulder portion and the center portion at the time of grounding is easily absorbed. Although uneven wear such as uneven wear can be prevented, many cords embedded in these reinforcing plies incline at a small angle with respect to the tire equatorial plane and cut ends at both ends in the width direction of the reinforcing ply. If the cord is exposed, the restraint in the circumferential direction largely depends on the shear deformation of the rubber layer between these reinforcing plies (the load on the cord itself is not so large), so the hoop tightening effect decreases. is there.

For this reason, the inventors of the present invention have diligently studied and, if the reinforcing layer is composed of one or two layers of spirally cord-arranged cords in the circumferential direction, the cord itself can be arranged in the circumferential direction. It was found that the restraint became effective and a strong rattling effect could be obtained.

However, it was found that in this case, only the tread (rib) in the region overlapping with the reinforcing layer was rapidly worn (rib punch). The reason for this is that if the circumference of the reinforcing layer is slightly deviated to the longer side, that is, if there is slack, the extra length causes the reinforcing layer and the ribs in the region overlapping with the reinforcing layer in the circumferential direction. It is considered that this is because the corrugation is caused, and as a result, the concave part that corresponds to the valley of the corrugation becomes a side to be dragged at the time of contact with the ground and slip occurs between the concave part and the road surface, and the concave part is rapidly worn.

In order to eliminate such uneven wear, further intensive research was conducted, and the land portions on both outer sides in the width direction of the region overlapping with the reinforcing layer were divided into independent blocks by the lateral grooves, and these lateral grooves became nodes and became a node at the time of ground contact. It has been found that the diameters of the both outer land portions can be reduced, whereby the radius of the both outer land portions approaches the radius of the recessed portion, the ground contact pressure is made uniform over a wide range, and the rib punch can be suppressed.

This invention was made based on the above findings,
A carcass layer forming a radial arrangement of steel cords extending in a toroidal shape, a cylindrical tread provided outside the crown portion of the carcass layer, and arranged between the carcass layer and the tread, and with respect to the tire equatorial plane 10 A steel belt comprising at least two layers of steel cords arranged in a direction intersecting each other in an angle range of 40 to 40 degrees, the belt layer extending substantially over the width of the tread, and the treads extending in parallel with each other; or 1 or 2 center ribs located in the center of the tread by 5 circumferential main grooves, a pair of side ribs sequentially located on both sides of the center rib and a pair of end ribs. In the pneumatic radial tire to be formed, between the carcass layer and the tread in the area corresponding to the center rib of the tread. A reinforcing layer consisting of one or two layers of cords arranged spirally in the circumferential direction is provided, while the side ribs adjacent to both sides of the area reinforced by the reinforcing layer are separated by a plurality of lateral grooves in the circumferential direction. It consists of block-shaped circumferential land rows.

Action The present invention has a narrow width of the reinforcing layer as described above,
Since the cord of this reinforcing layer itself exerts a binding force in the circumferential direction, the reinforcing layer exerts a strong ratchet tightening effect, and it is possible to reliably suppress the diameter expansion of the tire based on the internal pressure filling, and the belt end separation is effective. Can be stopped. Further, even when the center rib overlapping this reinforcing layer is wavy in the circumferential direction, the side rib that is not restrained by the reinforcing layer is formed with a lateral groove functioning as a node to form a concave portion of the center rib. Since the side ribs are made to follow and have a reduced diameter, the ground contact pressure becomes uniform, and rapid wear of the recess, that is, rib punching can be prevented.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 1, 2, and 3, reference numeral 1 is a pneumatic radial tire mounted on a truck or the like and used under a high internal pressure and a high load. The tire 1 has a carcass layer 2 extending in a toroidal shape. The layer 2 comprises at least one carcass ply 3 in this example. Each carcass ply 3 has a large number of reinforcing steel cords 4 embedded therein, and these cords 4 are arranged in a substantially radial direction, that is, in a direction substantially orthogonal to the tire equatorial plane 5. Both ends of the carcass layer 2 are folded back around the ring-shaped bead 6. Reference numeral 7 denotes a cylindrical tread that is arranged radially outside the crown portion of the carcass layer 2, and the tread 7 has four or five circumferential main grooves 8a, 8b, 8c, 8d extending parallel to each other on the outer circumference. Four, in this embodiment, four are formed apart from each other in the width direction. As a result, the outer circumference of the tread 7 is located at the center of the tread due to these main grooves 8a, 8b, 8c, 8d.
The center rib 9a is divided into a book-shaped center rib 9a, and a pair of side ribs 9b and a pair of end ribs 9c which are sequentially adjacent to each other on both sides in the width direction of the center rib 9a. The main groove 8
In the case of five, the central main groove 8 is located on the tire equatorial plane 5, but the center rib in this case is the two central ribs. Between the tread 7 and the carcass layer 2 there is arranged an annular belt layer 10 which extends substantially over the width of the tread, the belt layer 10 being at least two layers, in this embodiment two layers of belt plies 11. It consists of These belt plies 11 are provided with a number of reinforcing steel cords 12 at 10 degrees to 40 degrees with respect to the tire equatorial plane 5.
They are arranged in an angular range of degrees. And this belt layer
At least two layers of the belt plies 11 forming the sheet 10 are arranged such that the steel cords 12 intersect each other. Reference numeral 13 is a reinforcing layer composed of one or two layers of reinforcing ply 14, and the reinforcing layer 13 is provided between the tread 7 and the carcass layer 2, and in this embodiment, the belt layer 10 and the carcass layer 2.
It is placed between and. The reinforcing layer 13 is the tread 7
And the belt layer 10 or between the belt plies 11 may be arranged. Further, cords 15 arranged in a spiral shape in the circumferential direction are embedded in these reinforcing plies 14. here,
The reinforcing layer 13 is composed of one or two layers of the reinforcing ply 14 because when the reinforcing ply 14 has three or more layers, the gauge in the radial direction including the tread 7, the belt layer 10 and the reinforcing layer 13 becomes thick. This is because it becomes harmful in terms of heat generation. As described above, the spiral cords 15 are arranged on each reinforcing ply 14 to reinforce the reinforcing layer 13.
Since it has a strong ratchet tightening effect, the shearing force between plies at the belt end at the time of internal pressure filling is reduced, and the belt end separation is suppressed. Further, since the reinforcing ply 14 in which the cords 15 are arranged as described above cannot substantially expand and contract, if one circumference of the reinforcing ply 14 is deviated to the longer side, that is, if there is slack, the reinforcing ply 14 is reinforced. The surface of the tread 7 overlapping the ply 14 becomes wavy. When undulation occurs in this way, the recess that is in contact with the valley of the wave at the time of contact with the ground is dragged and slips against the road surface, causing rapid wear. Therefore, the reinforcing layer 13 is arranged in a region corresponding to the center rib 9a, and a pair of side ribs 9b adjacent to both sides of the region reinforced by the reinforcing layer 13 are circumferentially separated from each other so that both ends are main grooves 8a, 8b. , 8c, 8d with multiple lateral grooves
It was divided at 21. As a result, each side rib 9b composed of the circumferential land portion row divided into independent blocks by the lateral grooves 21 is easily deformed and reduced in diameter at the time of contact with the lateral grooves 21 as a node, and the radius thereof is the radius of the recess. Approach. Therefore, the ground pressure is made uniform over a wide range, rapid wear in the recess is suppressed, and rib punching is prevented. Here, the reason why the reinforcing layer 13 is arranged in the area corresponding to the center rib 9a as described above is as follows. That is, when the widthwise end of the reinforcing layer 13 is extended to the widthwise outer side from the area corresponding to the center rib 9a, the reinforcing layer is formed.
The rattle tightening effect of 13 also acts on the side ribs 9b to improve the rigidity of the side ribs 9b, which makes it difficult to reduce the diameter at the time of contact with the ground, and the rigidity of the side ribs 9b varies depending on the position in the width direction. This is because only the edge portion of 9b is unevenly worn (river wear). The lateral groove 21 is a sipe that opens in the main groove and closes at the time of contact with the ground, but the lateral groove 21 may be a wide main groove that does not close at the time of contact with the ground. The lateral groove 21 may be linear, may be bent in a zigzag shape, or may be curved.

Next, a test example will be described. Before starting this test, comparative tires 1 and 2 having a size of 10.00R20 and test tires 1, 2, 3, 4, and 5 were prepared. Comparison tire 1
As shown in FIGS. 4 (a) and 4 (b), the widthwise both outer ends 17 and 18 of the reinforcing layer 13 are located inward in the widthwise direction from the area corresponding to the center rib 9a. As shown in FIGS. 4 (c) and 4 (d), the comparative tire 2 has lateral grooves 21 formed on each side rib 9b, but the lateral tire 21 does not have lateral grooves. In the tire, 17 and 18 are positioned further outward in the width direction than the area corresponding to the center rib 9a. Further, the test tire 1 is shown in FIG. 4 (e).
As shown in (f), the lateral groove 21 described in the above embodiment is a sipe tire, and the test tire 2 is shown in FIG. 4 (g).
As shown in (h), the tire described in the above embodiment is a tire in which the lateral groove 21 is changed from a sipe to a wide main groove, and the test tire 3 is as shown in FIG. 4 (i) (j). ,
A wide range of reinforcing plies 31 (widthwise both outer ends)
32 is a tire in which a reinforcing ply located outside the area corresponding to the center rib 9a in the width direction is added between the reinforcing layer 13 and the belt layer 10, and the test tire 4 is shown in FIG. 4 (k).
As shown in (l), in the tire described in the above embodiment, the reinforcing layer 13 is changed in position from between the belt layer 10 and the carcass layer 2 to between the belt layer 10 and the tread 7, As shown in FIGS. 4 (m) and (n), the test tire 5 is a tire having five main grooves 8 and a reinforcing layer 13 arranged in an area corresponding to two center ribs 9a located in the central portion. . These tires are modeled as 2D-4 (1 front wheel
The axle and the rear wheel are two axles, and one of the rear axles is the drive axle,
And 8.0k after being mounted on the front wheel of a flat body truck of the type (4 tires were mounted on each axle of the rear wheel)
It was filled with an internal pressure of g / cm ² and traveled 120,000 km on a pavement highway of 80% and a pavement general road of 20% at a loading rate of 100%. Next, the tread of each tire after running was inspected. As a result, the comparative tire 1 has a depth of 1.8 m in the center rib 9a.
Rib punch of m occurred, and side rib 9
There was riverwear with a width of 7.0 mm and a depth of 2.0 mm on b. On the other hand, the test tires 1, 3, 4, and 5 had almost no uneven wear, and only the test tire 2 had slight heel and toe wear on the side ribs 9b. As described above, the comparative tires that deviate from the scope of the present invention had uneven wear to a considerable extent, but the test tires to which the present invention was applied hardly had uneven wear, and the uneven wear It was possible to prevent the occurrence of. Moreover, after running, each test tire was cut and the belt end was inspected, but almost no cracks were generated,
Belt end separation was also prevented with certainty.

As described above, according to the present invention, both belt end separation and uneven wear can be reliably prevented.

[Brief description of drawings]

FIG. 1 is a meridian sectional view of a tire showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of part A of FIG. 1, FIG. 3 is its tread development view, and FIGS. ) Is a tread development view and a meridian sectional view of the tire used in the test. 2 ... Carcass layer, 4 ... Steel cord 5 ... Tire equatorial plane, 7 ... Tread 8 ... Main groove, 9a ... Center rib 9b ... Side rib, 9c ... End rib 10 ... Belt layer, 12 ... … Steel cord 13 …… Reinforcing layer, 15 …… Code 21 …… Horizontal groove

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B60C 11/12 7504-3B B60C 11/06 B (56) Reference JP-A-54-126308 (JP, A) JP-A-56-17705 (JP, A) JP-A-59-176104 (JP, A) JP-A-60-255507 (JP, A) JP-B 44-19201 (JP, B1) JP-B 59-2641 (JP, B1) Japanese Patent Publication Sho 31-2202 (JP, B1)

Claims (1)

(57) [Claims] 1. A carcass layer having a radial arrangement of steel cords extending in a toroidal shape, a cylindrical tread provided outside the crown portion of the carcass layer, and a carcass layer disposed between the carcass layer and the tread. To face
4 steel layers comprising at least two layers of steel cords arranged in a direction intersecting each other in an angle range of 10 to 40 degrees and including a belt layer extending substantially over the width of the tread, the treads extending in parallel with each other. Alternatively, one or two center ribs located in the central portion of the tread by the five circumferential main grooves, a pair of side ribs sequentially located on both sides of the center rib, and a high internal pressure divided into a pair of end ribs under high load. A pneumatic radial tire to be used, comprising a reinforcing layer consisting of one or two layers in which cords are spirally arranged in the circumferential direction between a carcass layer and a tread in a region corresponding to the center rib of the tread. On the other hand, the side ribs adjacent to both sides of the area reinforced by the reinforcing layer are independent block-shaped circumferential directions divided in the circumferential direction by a large number of lateral grooves. A pneumatic radial tire characterized by consisting of a land line.